TRIM5α requires Ube2W to anchor Lys63-linked ubiquitin chains and restrict reverse transcription.
TRIM5α requires Ube2W to anchor Lys63-linked ubiquitin chains and restrict reverse transcription.
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DOI：
10.15252/embj.201490361
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发表时间：
2015-08-04
期刊：
影响因子：
--
通讯作者：
Towers GJ
中科院分区：
文献类型：
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作者：
Fletcher AJ;Christensen DE;Nelson C;Tan CP;Schaller T;Lehner PJ;Sundquist WI;Towers GJ
TRIM 5 α是一种抗病毒的细胞质E3泛素（Ub）连接酶，在进入的逆转录病毒衣壳上组装并诱导其过早解离。它抑制病毒基因组的逆转录，还可以合成未锚定的聚泛蛋白（polyUb）链以刺激先天免疫反应。在这里，我们发现TRIM 5 α在TRIM 5 α自身泛素化过程中使用E2 Ub缀合酶Ube 2 W来锚Lys 63连接的polyUb链。在细胞内和体外，通过Ube 2 W催化的TRIM 5 α的单泛素化启动链锚定。这种修饰充当锚定的Lys 63连接的polyUb链的延长的底物，由异二聚体E2酶Ube 2N/Ube 2 V2催化。Ube 2 W与Ub靶向多个TRIM 5 α内部赖氨酸，特别是赖氨酸45和50，而不是修饰N-末端氨基，其在细胞中被α N-乙酰化。E2缺失或Ub突变抑制细胞中TRIM 5 α泛素化并恢复限制性病毒逆转录，但不抑制感染。我们的数据表明，逐步形成锚定的Lys 63连接的polyUb是TRIM 5 α限制机制的关键早期步骤，并确定了参与的E2 Ub缀合辅因子。
TRIM5α is an antiviral, cytoplasmic, E3 ubiquitin (Ub) ligase that assembles on incoming retroviral capsids and induces their premature dissociation. It inhibits reverse transcription of the viral genome and can also synthesize unanchored polyubiquitin (polyUb) chains to stimulate innate immune responses. Here, we show that TRIM5α employs the E2 Ub-conjugating enzyme Ube2W to anchor the Lys63-linked polyUb chains in a process of TRIM5α auto-ubiquitination. Chain anchoring is initiated, in cells and in vitro, through Ube2W-catalyzed monoubiquitination of TRIM5α. This modification serves as a substrate for the elongation of anchored Lys63-linked polyUb chains, catalyzed by the heterodimeric E2 enzyme Ube2N/Ube2V2. Ube2W targets multiple TRIM5α internal lysines with Ub especially lysines 45 and 50, rather than modifying the N-terminal amino group, which is instead αN-acetylated in cells. E2 depletion or Ub mutation inhibits TRIM5α ubiquitination in cells and restores restricted viral reverse transcription, but not infection. Our data indicate that the stepwise formation of anchored Lys63-linked polyUb is a critical early step in the TRIM5α restriction mechanism and identify the E2 Ub-conjugating cofactors involved.